Momentary switch having normally engaged contacts actuated by a conductive member



y 9, 1953 P. N. CRAWFORD ETAL 3,392,252

MOMENTARY SWITCH HAVING NORMALLY ENGAGED CONTACTS ACTUATED BY ACONDUCTIVE MEMBER Filed Aug. 4, 1966 FIG 5 PH/L /P N. CRAWFGRD WAL TE E.TAYLOR INVENTORS United States Patent 3,392,252 MOMENTARY SWITCH HAVINGNORMALLY ENGAGED CONTACTS ACTUATED BY A CONDUCTIVE MEMBER Philip N.Crawford and Walter E. Taylor, Rochester,

N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporationof New Jersey Filed Aug. 4, 1966, Ser. No. 570,206 7 Claims. (Cl.200-160) ABSTRACT OF THE DISCLOSURE A momentary break switch hasnormally engaged contacts which, upon actuation of a push button, areurged apart by a blade member of electrically conducting material. Theelectrical path between the contacts is maintained by the blade memberuntil it passes from between the contacts, then allowing the contacts tospring together but interrupting the electrical path there-between priorto their re-engagment for a substantially uniform increment of time,regardless of the rate of actuation of the push button.

This invention relates to an electrical switch mech anism and moreparticularly to an electrical switch which is normally closed but isopened momentarily upon de pression of an associated push button.

The utilization of make and break switching arrangements has becomeincreasingly important with the rapid development of electrical controlsystems. With the advent of increased technology and sophistication insystems of this type, a demand has been created for switches which willoperate in a uniform manner during repetitive use over an extendedperiod of time.

It is therefore an object of this invention to provide an improvedelectrical switch which is normally closed and which can be opened onlymomentarily and for a substantially uniform increment of time, uponmovement of an associated push button or other actuating means,regardless of the rate of movement thereof.

It is a further object of this invention to provide a momentary break,electrical switch which is characterized by simplicity of constructionand ease of operation, such switch during its normal operation cyclebeing continuously closed except for a brief predetermined increment oftime while the associated push button is depressed.

These objectives have been attained in the present invention byproviding a pair of normally engaged switch contacts which are urgedapart upon depression of a push button or other actuating means by ablade member of electrically conducting material, said blade memberbeing disengaged from the contacts as the push button reaches the end ofits depressed path, thus allowing the contacts to spring together butinterrupting the electrical contact therebetween prior to theirre-engagement.

Other objects of the invention will appear from the followingdescription, reference being made to the accompanying drawings wherein:

FIG. 1 is an isometric view of an electrical switch incorporating theelements of the invention disclosed herein;

FIGS. 2, 3, 4, and are schematic illustrations showing positions assumedby certain elements of the device of FIG. 1 during various stages in theoperation thereof.

Referring now to FIG. 1, a base plate 10 is shown in phantom. Embeddedin base plate 10 is a hollow circular guide member 11 open at the upperend thereof and closed at its bottom. Guide member 11 is constructed ofplastic or any other non-conductive material. Reciprocatably mounted inguide member 11 for sliding movement therein is a circular base member12 having a control button 13 projecting therefrom.

As may readily been seen, circular base member 12 has a hollow recessdisposed at the lowermost end thereof which accommodates the upperportion of a coil compression spring 14. The lower portion of coilspring 14 rests on the bottom wall of circular guide member 11. Circularguide member 11 has elongated slots 15, 16 on opposite sides thereof.Base member 12 has a pair of additional slots 15a, 16a and is positionedso that slot 15a is in alignment with elongated slot 15 and slot 16a isin alignment with slot 16. Projecting through all four slots is a blade17 which is constructed of an electrically conductive material and isfixedly attached at one end thereof to the upper portion of coil spring14 by any known expedient for the purpose which will be more fullydisclosed below.

Attached to base plate 10 and positioned in the mannot illustrated arefixed switch contact 18 and movable switch contact 19, both of which areconstructed of an electrically conductive material. Movable contact 19in cludes contact plate 19a and a resilient L-shaped member 19b which isself-biased so as to be resiliently urged into abutting position withfixed contact 18.

The operation of the device will now be described. Referring now toFIGS. 1 and 2, the elements of the device are shown in their normal restposition. As described above, L-shapecl member 19b of movable contact 19is in abutting position with fixed contact 18. Electrical current isthus free to flow through said contacts. Blade 17, under the resilienturging of coil spring 14, is yieldably positioned against fixed contact18. As may most clearly be seen with reference to FIG. 2, the contactingportion of blade 17 is bent slightly so that the uppermost portionthereof is turned away from fixed contact 18. Upon depression of controlbutton 13, blade 17 moves in a downward direction thereby cammingresilient L-shaped member 19b of movable contact 19 in the directionindicated by the arrow in FIG. 2, away from fixed contact 18 and to anew position which may most clearly be seen in FIG. 3. Electricalcurrent, however, continues to flow through fixed contact 18 and movablecontact 19 by virtue of the fact that blade 17 is constructed ofelectrically conductive material. When blade 17 reaches the positionillustrated in FIG. 4, resilient L-shaped member 19b jumps off theuppermost portion of blade 17 and moves to the position illustrated insolid lines. It is during this brief interval after the L-shaped member19b jumps off blade 17 and before it hits fixed contact 18 that currentflow is momentarily halted between fixed contact 18 and movable contact19.

As the operator relieves pressure from control button 13, control button13 and blade 17 are urged in an upward direction under the influence ofcoil spring 14. The outwardly bent end portion of blade 17 now moves inthe direction of the arrow shown in FIG. 4, and rides over L-shapedmember 19b in the manner shown in FIG. 5. During this return movement ofcontrol button 13 and blade 17, movable contact 19 and fixed contact 18remain in abutting or engaged position thus allowing the flow of currentto continue therebetween.

It will thus be seen that the time interval during which current failsto flow between contact 18 and contact 19 remains substantiallyconstant, regardless of the speed with which control button 13 and blade17 are depressed by the operator, since such time interval is determinedonly by the snapping action of L-shaped member 19b. In addition, thepresent arrangement, due to the wiping action of blade 17 as it movesbetween contacts 18 and 19, provides for the maintenance of clean switchcontact surfaces.

Having described the general form of the present invention, it should beunderstood that the form illustrated herein has been selected tofacilitate the disclosure of the invention rather than to limit thenumber of forms which it may assume, and various modifications,adaptations, and alterations may be applied to the form shown to meetthe requirements of practice without departing from the spirit or scopeof the present invention. For example, the switch actuating means may beof any known type and need not be manually operable.

We claim:

1. In an electrical switch mechanism:

(a) a pair of normally abutting switch contacts;

(b) actuating means movable over a predetermined path from a firstposition to a second position and back to said first position;

(c) electrically conductive means responsive to movement of saidactuating means for passing between said contacts as said actuatingmeans moves from said first position to said second position therebyseparating said contacts but maintaining a flow of electrical currentbetween said contacts while between and engaging said contacts;

(d) said electrically conductive means and said contacts having meanscooperating (1) to interrupt electrical current flow between saidcontacts for a predetermined time as said electrically conductive meanspasses wholly from between said contacts and (2) to maintain electricalcurrent flow through said contacts after said predetermined time and assaid actuating means returns to its said first position.

2. The electrical switch mechanism according to claim 1 wherein saidelectrically conductive means comprises a blade member having a bent endportion which is adapted to exert a camming action upon at least one fsaid contacts as said blade member passes between said contacts andwhich permits said contacts to snap together after passing therebetween,thereby briefly interrupting current flow between said contacts.

3. The electrical switch mechanism according to claim 1 wherein a singlecoil spring is provided for biasing said actuating means toward saidfirst position and for yieldably maintaining said electricallyconductive means on one of said contacts.

4. The electrical switch mechanism according to claim 1 wherein saidelectrically conductive means exerts a wiping action on the surfaces ofsaid contacts as it passes therebetween.

5. An electrical switch having an open state and a closed state, saidswitch comprising two contacts biased toward one another so that saidcontacts are normally touching and the switch is normally closed;conductive means adapted to be inserted between said contacts toseparate them while maintaining the switch in a closed state, and meansfor withdrawing said conductive means from said contacts along one ofsaid contacts so that when said conductive means clears said one contactthe switch is in an open state for a brief predetermined period of time.

6. In an electrical switch mechanism:

(a) a pair of normally engaged switch contacts;

(b) actuating means movable over a predetermined path from a firstposition to a second position;

(c) electrically conductive means responsive to movement of saidactuating means for passing between said contacts as said actuatingmeans moves from said first position to said second position therebyseparating said contacts while maintaining the switch closed;

(d) said electrically conductive means and said contacts cooperating tointerrupt electrical current flow between said contacts for apredetermined time as said electrically conductive means passes whollyfrom between said contacts.

7. An electrical switch hasing an open state and a closed state, saidswitch comprising two contacts at least one of which is biased towardthe other for closing the switch; conductive means positionable betweensaid contacts to separate them while maintaining the switch in a closedstate, and means for withdrawing said conductive means from saidcontacts so that the switch is in an open state for a briefpredetermined period of time.

References Cited UNITED STATES PATENTS 1/1937 Schellenger 200164 XR4/1940 De Vincenzi 200

